How to test your home for radon

You can't see, smell or taste radon, and a test is the only way to know your level. Radon is the second leading cause of lung cancer in the United States, after smoking. Every home below the third floor needs a test. A do-it-yourself kit costs little and takes a few minutes to set up.

What you need

• A short-term radon test kit, sold by mail and in some hardware stores
• The kit's instructions and its prepaid mailer to the lab
• A spot in a lived-in room, at least 20 inches off the floor

Steps

1. 1

   Close up the house

   For a 2- or 3-day test, close the windows and outside doors at least 12 hours before you start. Keep them closed through the test. The heating and air conditioning fan can run, but not a fan that brings in outside air.

   5 min

2. 2

   Pick the room

   Use the lowest lived-in level: the basement if you use it often, otherwise the first floor. Choose a room you use regularly, such as a living room or a bedroom, but not the kitchen or a bathroom.

   5 min

3. 3

   Set out the kit

   Place it at least 20 inches above the floor, away from drafts, high heat, high humidity and outside walls. Leave it as long as the package says.

   5 min

4. 4

   Mail it to the lab

   Reseal the package and send it to the lab on the package right away. Results arrive within a few weeks.

   5 min

5. 5

   Read the result against 4 pCi/L

   Radon is measured in picocuries per liter of air, written pCi/L. The lab's report gives the number to compare.

   2 min

Don't run a 2- or 3-day test during unusually severe storms or high winds.

What the result means

If the first short-term result is 4 pCi/L or higher, take a follow-up test to be sure. Use a long-term test for a better picture of the year-round average, or a second short-term test if you need the answer quickly. If the first result is more than twice the 4 pCi/L action level, take the second short-term test right away.

The average indoor level is about 1.3 pCi/L, against about 0.4 pCi/L outdoors. Between 2 and 4 pCi/L, fixing the house is still worth considering.

If the level is high

Lowering radon takes technical knowledge and special skills, so the work goes to a contractor trained to fix radon problems. Your state radon office can give you names of qualified or state-certified radon contractors. Some reduction systems lower radon levels by up to 99 percent.